This type of thinking tends to confuse a common law criminal with a person actively engaged in war against the United States. Imagine a German American in 1941 going to Germany and joining the Wehrmacht. Would the author of this article then claim he should be hunted down, arrested and tried in a court? No he would have died on the Battle field as he should.
Targeted for an assassination, or confronted as another enemy combatant on a battle field facing the normal procedure of war offensives? I think the quailing is about targeting for an assassination. This is the edge of the wedge.
So who decides who is a terrorist? Militia organizations have been deemed hate groups in America. Not such a big leap from hate group to terrorist. Are they fair game for drones while outside the continental US?